During World War II, millions of Americans grew food in their backyards, eventually supplying a hungry nation with 40 percent of its fruits and vegetables. Urban farming is making a comeback today. It is proposed as the solution for “food deserts” in poor neighborhoods and cities have set up programs encouraging people to grow crops in vacant lots or on rooftops. But does it work? Here’s an analysis by Vox: Urban farming may never feed whole cities, but it does revitalize communities and encourages healthier diets.